You want to know how Avalara handles discounts in QuickBooks Desktop.
Current discount method:
Discount lines are treated as negative lines, and appear as lines in the Avalara AvaTax Admin Console. This method allows for discount items to be mapped to specific tax codes in the Avalara AvaTax Admin Console. This method of handling discounts makes a lot of sense as long as the user chooses the correct discount item.
Previous discount method:
A discount line would reduce the value of the line directly above it on the document. This could make the line above become negative even. This method did not have discount lines appear at all on the Avalara AvaTax Admin Console. Arguably, the biggest issue with this method was it was less obvious how to make a discount non-taxable, even if it is being applied to a taxable item (for example cell phones in California must be taxed at the full retail price). This method is more convenient for people that simply want to use only one discount item in QuickBooks. They simply place it below an item on their invoice and the tax code will match (since it simply reduces the value of the line above it).